Hey! Welcome to the United States. May we have your Twitter handle, please?

That's exactly what you'll likely be asked by the U.S. Customs and Border Protection at the airport prior to entering U.S. soil.

Yes, your Twitter handle may soon be part of the US Visa process as U.S. Customs and Border Protection has entered a new proposal into the federal register, suggesting a new field in which foreign visitors can declare their online presence.

This new proposal submitted by the US Department of Homeland Security (DHS) to the Federal Register on Thursday would update the required entry forms with a question asking travelers to "Please enter information associated with your online presence -- Provider/Platform -- Social media identifier."

This information would not be mandatory, but of course, foreign travelers who decline to reveal their online presence may subject for additional scrutiny.

What's the idea behind Knowing the visitors' Online Presence?

According to DHS, the social media snooping would add a new level of scrutiny to potential foreign visitors, who are already photographed, fingerprinted, and in-person interviewed, alongside numerous database checks.

"Collecting social media data will enhance the existing investigative process and provide DHS greater clarity and visibility to possible nefarious activity and connections by providing an additional tool set which analysts and investigators may use to better analyse and investigate the case," reads the proposal.

The new field would be added to the Electronic System for Travel Authorisation (ESTA) and Form I-94 that is used as a record to notify United States authorities in advance of their arrival to and departure from the country.

US Customs and Border Protection is seeking comments on the new proposal until August 22. So, the public has 60 days to write to the agency's Washington, D.C. office before the proposal is formally considered.

Tracking - Biggest Privacy Concern in the Digital World

The United States is not the only nation that wants to track foreign visitors. Many countries have their own way through which they track visitors.

The Canadian spy agency tracks foreign travelers even days after they left the terminal, by capturing their device identification from the free Wi-Fi hotspots at a major Canadian airport, according to documents revealed by Edward Snowden.

However, tracking is illegal. Just recently, a Singapore-based InMobi mobile advertising company that tracked the locations of hundreds of Millions of users without their consent agreed to pay $950,000 in penalties to settle charges of violating federal law.

At last, just answer me…

Will any potential bad actor or terrorist, if asked, reveal their online presence?

Also, if this technique will actually prevent terrorists from entering the country, then what about the potential terrorists who already live in the US or are U.S. citizens?